The present invention relates to a navigation system, and a method for operating it, having a navigation computer, a data carrier reading device, and a navigation data carrier, the navigation data of possible destinations stored on the navigation data carrier being able to be read out using the data carrier reading device and to be read into a working memory of the navigation computer. In addition, the present invention relates to a navigation data carrier having navigation data stored in it as well as a method for generating it.
In propulsion devices, such as motor vehicles, aircraft, or ships, permanently installed navigation systems guide a driver of the means of propulsion from a current location to a desired destination quickly, simply, and reliably, without the driver of the means of propulsion having previously to plan a route in detail and to acquire the corresponding map materials. For this purpose, the appropriate navigation data, based, for example, on maps, area maps, or street maps, are stored in the navigation system, for example on CD-ROMs. The navigation device makes use of, for example, GPS (Global Positioning System) to determine an instantaneous location and to calculate the corresponding navigation instructions, which lead to a predetermined destination. In this context, the navigation data may contain data on streets and routes for motor vehicles.
However, before the navigation system can take on its task and calculate a route from the current location to the destination, it is necessary that a user enter the desired destination and, in navigation devices without GPS, also the current location. This occurs, for example, via a voice-operated system. In voice-operated navigation of this type using phonetic characters, a so-called list matching is necessary. This denotes a comparison of a letter-hypothesis of a voice recognition unit with possible destinations, such as cities, street names, or special destinations in the list of possible destinations. Of use for the list matching are, on the one hand, data from the voice-operated system, the aforementioned hypotheses, and, on the other hand, a list of possible destinations, which is stored, for example, on a navigation CD-ROM as input data.
In conventional voice recognition systems, the list of possible destinations is loaded in a working memory of a computer and is kept there. However, this has the disadvantage of requiring a great deal of memory space and is therefore very uneconomical, since navigation systems that are furnished with voice- recognition systems of this type are very cost-intensive and are therefore not competitive on the market. It is therefore necessary to transfer the data for the list comparison from the navigation CD-ROM to the working memory of the computer of the navigation system only at those times in which the list of possible destinations is actually required. However, since the data on the navigation CD-ROM are available sorted according to corresponding index references, reading out the data from the navigation CD-ROM is very time-consuming because the read head of a CD-ROM disk drive must again and again travel back and forth between the index table and actual data and, accordingly, must be repositioned each time. The result is long transfer times for the list of possible destinations, from the navigation CD-ROM to the working memory of the computer of the navigation system.
An object of the present invention is to provide an improved navigation system, an improved method for operating it, an improved navigation data carrier of the above-mentioned type as well as an improved method of the above-mentioned type for writing onto a navigation data carrier, such that the above mentioned disadvantages are removed and a cost-effective use of a voice-controlled system is achieved for a navigation system.
In a navigation system according to the present invention, the navigation data carrier is configured such that the navigation data are stored on it in sequential form so as to be able to be read out in one read operation.
In addition, in a method for operating this navigation system, it is provided according to the present invention that the navigation data are read out from the navigation data carrier sequentially, in one single read operation, and are read into the working memory of the navigation computer.
This has the advantage that the navigation data can be read out completely, in sequence, and without requiring a repositioning of the read head of the data carrier reading device, resulting in a particularly short transfer time of the navigation data from the navigation data carrier into the working memory of the navigation computer. In this manner, it is possible to integrate in a navigation system a voice-controlled system in which the navigation data for the voice recognition are only stored temporarily in the working memory and this working memory is otherwise available for other tasks or processes of the navigation system. Thus, to a significant degree, the use of the working memory is economized, resulting in a more cost-effective navigation system.
Time is also saved in the transfer of navigation data from the navigation data carrier into the working memory of the navigation computer as a result of the fact that the navigation data on the navigation data carrier are stored in compressed form.
In an example embodiment, the data carrier reading device is a CD-ROM disk drive and the data carrier is a navigation CD-ROM.
According to the present invention navigation data on the navigation data carrier (e.g./a CD-ROM) are stored sequentially, such that the navigation data can be read out sequentially in one single read operation.
In a method according to the present invention, navigation data are stored sequentially, one set of data immediately following the other, on the navigation data carrier.
This has the advantage that the data can be read out completely in one single read operation by a data carrier reading device of a navigation system in a directly sequential manner, without placing or repositioning a read head.
Because the navigation data is compressed before being written onto the navigation data carrier, it is advantageously possible that the navigation data, upon being read out by a data carrier reading device of the navigation system, can be written directly into the working memory of the navigation computer without further conversion. This additionally reduces the time necessary for the transfer of the navigation data from the navigation data carrier to the working memory of the navigation computer.
In this context, the present invention is based on the knowledge that storing data on a CD-ROM using an index list helps achieve the goal of being able to set the read head of a CD-ROM disk drive at any point on the data on a CD-ROM and to be able to read out a desired excerpt of the data on the CD-ROM without having to read all of the data previously stored on the track of the CD-ROM. However, this is not required for the application of the navigation CD-ROM in a navigation system using a voice-controlled system, since for the voice recognition here, the entire content of the navigation CD-ROM, in any case, must temporarily be read into the working memory of the computer of the navigation system.